1. Field of the Invention
The present invention generally relates to a power grid, and more specifically, to a method and system for detecting conflicts between outage requests and power supply guarantee requests in a power grid.
2. Background of the Related Art
With the acceleration of the use of electricity in the whole of society and the market development of the electric power industry, people increasingly rely on electric power. The power grid is a key component of an electric power system, and plays the role of transmitting a large capacity of power. In order to transmit electric power more reliably and efficiently, the concept of a “smart grid” has been proposed in recent years. Based on the so-called smart grid, a large number of new techniques are applied in power generating, power transmitting, power distributing, power using and etc., to optimize the configuration of the power grid, save energy and reduce emissions. Intelligent Outage Plan Management is an important part of the smart grid, which helps to manage outages in the grid more efficiently.
Power grid companies usually need to handle power supply guarantee requests (PSGR) and outage requests (OR). For example, in order to perform ordinary maintenance or technical renovation/upgrade, or coordinate with municipal reconstruction, power grid companies need to stop or cut off the electric power of certain electric power devices to ensure the safety of workers. A request to cut off the power supply to an electric power device is referred to as an Outage Request. On the other hand, power grid companies need to guarantee the power supply for some important events or users. Important events for example include a college entrance examination or an important conference. Important users for example include government departments and special industry users (e.g. iron and steel factory). A request to guarantee the power supply for an electric power user is referred to as a Power Supply Guarantee Request (PSGR).
An outage request may be related to electric power devices including a transformer, power line, breaker, bus bar, secondary device, etc. A power supply guarantee request usually relates to the guarantee of power supply for an organization or event, however, the organization or event is associated with fixed buildings or facilities. Therefore, power supply guarantee requests related to electric power devices mainly refer to distribution transformers associated with buildings or facilities requiring the power supply guarantee. As long as it is guaranteed that the power to a corresponding distribution transformer will not be cut off, it can guarantee the power supply for one or more buildings or facilities associated with this distribution transformer.
In practice, PSGRs and ORs often have conflicts. Power grid companies need to judge if the fulfilling of an OR will cause a conflict with a PSGR, and adjust an operating mode to ensure the PSGR as much as possible.
An example of a conflict arising between PSGR and OR in a power grid is illustrated in FIG. 1. In FIG. 1, hexagons refer to users, lines refer to power lines, and user C is a user with a PSGR. In the event of maintaining line L1, the power supply for line L1 should be cut off. In addition, since line L2 and line L1 intersect with each other geographically, prior to the actual maintenance, in order to ensure safety when performing maintenance for line L1, the power supply to line L2 has to be cut off at the same time. On the other hand, due to the outage of line L2, it can be judged from FIG. 1 that power supply to users B and C both will be cut off, which obviously will produce a conflict with the PSGR for user C.
At present, power grid companies store received ORs and PSGRs in a power grid management information system. FIG. 2 schematically shows an example of all the PSGRs and ORs in a certain month, wherein each request lasts for a period of time. There are a plurality of ORs in FIG. 2, and in accordance with these ORs, for example, it is necessary to perform an outage for “line 5114” from the first day to the fifth day, to perform an outage for the “500 kV Bus Bar” from the fourth day to the eighth day, and to perform an outage for “No. 2 main transformer” from the twenty-first day to the twenty-fifth day, and so forth. There are also six PSGRs in FIG. 2. These PSGRs include user power supply guarantees, conference power supply guarantees and event power supply guarantees, each power supply guarantee lasting for several days. Though time related to ORs and PSGRs in FIG. 2 is in the unit of day, obviously, the time related to these requests can also be in the units of hours or minutes, etc. For example, one OR or PSGR can last from 20:05 in the first day to 8:30 in the third day precisely. Judging whether performing an outage for specific electric power devices in accordance with ORs will produce a conflict with PSGRs based on time points, has become a problem that power grid companies should resolve.
Traditionally, conflicts are detected manually. Grid dispatchers need to explore manually over the power grid topology and judge separately whether an OR will cause a conflict with a PSGR. This manual detection is based on power grid topology. However, the scale of grid is getting increasingly large. So, grid topology is becoming more and more complex. Therefore manual detection will consume much time. In addition, because the judgment is made manually, reliability can not be guaranteed and some conflicts might be missed.
In addition, there is system aided detection. The system aided detection is based on management information system (MIS) that uses simple name matching to verify if a PSGR device is among OR devices. That is, this system aided detection verifies if the PSGR device's name is among OR devices' name list. If the PSGR device's name is among OR devices' name list, then a conflict is detected. This system aided detection does not take grid topology into account. The scope of an outage is not limited to OR related outage devices, but extends from said outage device outwardly until reaching switches (or terminals or ground nodes). Therefore, the actual scope of an outage includes electric power devices not within the above outage devices' name list. In this case, even if a PSGR device is not among outage devices' name list, it may be affected by the actual outage. Thus, the system aided detection, in accordance with the prior art, is not reliable.